Photographic developer.



UNITED STATES Patented August 16, 1904.

PATENT OEEIcE.

BENNO HOMOLKA, OF FRANKFORT-ON-THE-MAIN, AND NIOOLAUS SCHNAN, OF SODEN,GERMANY, ASSIGNORS TO FARBWERKE, VORM. MEISTER, LUCIUS & BRUNING, OFHOOHST-ON-THE-MAIN, GERMANY, A CORPORATION OF GERMANY.

PHOTOGRAPHIC DEVELOPER.

SPECIFICATION forming par f Letters Patent N 76'7,815, dated. August 16,1904.

Application filed October 28, 1902.

To all lUhOHL it nuty concern.-

Be it known that we, BENNO HOMOLKA, Ph. D. residing atFrankfort-on-the-Main. and NIooLAUs ScHwAN, Ph.D., residing at Soden,Germany, citizens of the Empire of Germany, have invented certain newand useful Improvements in Photographic Developers, of which thefollowing is a specification.

Most of the substances now used in photography as developers react onthe latent photographic image only in the presence of fixed or volatilealkalies or alkali carbonates. This is well recognized as a drawback.The fixed alkalies and alkali carbonates are of injurious influence onthe gelatin coating of plates, which turns soft, swells up, and tends tocurl or float off, especially in hot weather or climates. With volatilealkalies, particularly ammonia, the volatility and disagreeable odor areinconveniently felt, apart from other drawbacks. It has been endeavoredfor some time to find a harmless substitute for these substances. Borax,sugar lime, potassium ferrocyanid, tribasic sodium phosphate, &c.,

have been proposed; but none of these have answered commercially. Afternumerous experiments in this direction a harmless substitute foralkalies in photographic developers satisfying all requirements has beenfound in the alkali salts of glycocoll.

By glycocoll we understand the amido acetic acid, as well as itsderivatives, having an alkyl group attached to the nitrogen, especiallymonomethyl and dimethyl amido acetic acid and monoethyl and diethylamidoacetic acid.

Especially favorable results have been obtained by employing the alkalisalts of glycocoll with the following developing agents:pyrogallol,hydroquinone, pyrocatechol, paraamido phenol, glycerin, (paraoxyphenyl Serial No. 129,157. (No model.)

glycin,) eikonogen, (amidonaphtholsulfonic acid,) adurol, (brom orchlorhydroquinone,) edinol, (oxyamidobenzyl alcohol.)

The manner of using the glycocoll alkalies withphotographic developersmay be illustrated by the following example:

In about one-halfliter of water are dissolved eighty grams ofcrystallized sodium sulfite and twelve grams of pyrogallic acid oreleven grams of hydroquinone, or the equivalent quantity of one of theabove-mentioned developing agents, glycin and eikonogen, in form oftheir alkali salts. To this mixture is added an aqueous solution oftwenty-four grams of glycocoll and twelve grams of caustic soda, thefinished solution being made up to one thousand cubic centimeters. Thissolution may be used directly to develop dry-plates of brom silvergelatin. If chlorbrom silver plates or emulsion papers are used, thesolution is diluted with the multiple volume of water. If necessary, aslight addition of alkali bromid will have a clarifying effect. Theimages after proper exposure appear rapidly and are distinguished bygreat clearness. The curling up or floating olf of the coat of gelatindoes not occur.

Having now described our invention, what we claim is A photographicdeveloper, containing a developing agent and an alkali salt ofglycocoll, substantially as set forth.

In testimony that we claim the foregoing as our invention we have signedour names in presence of two subscribing witnesses.

BENNO HOMOLKA. NICOLAUS SCHXVAN.

Witnesses:

ALFRED BRISBOIS, J OHANN HARTENSTEIN.

